Catalytic wall reactor – catalytic coating of stainless steel by VOx/TiO2 and Co/SiO2 catalysts

International audienceCatalytic wall (structured) reactors and structured supports are suitable to study the catalytic properties of nanosized materials. The coating of metallic (aluminum and stainless steel) plates by thin layers of active phase is presented in two cases, VOx/TiO2 and Co/SiO2, catalysts used in the oxidative dehydrogenation (ODH) of propane and in Fischer–Tropsch synthesis (FTS) of clean fuels, respectively. The preparation of coated plates and their characterisation by various methods of physicochemical analysis are described. Both chemical and physical methods were used for coating. VOx/TiO2 layers were obtained by grafting of Ti (on Al or stainless-steel plates) and V (on TiO2) alkoxides and use of sol–gel media or suspension. A silica primer was deposited (on stainless-steel plate) by plasma-assisted chemical vapour deposition (PACVD) onto which Co oxide and silica were coprecipitated from sol–gel. The catalytic experiments in the respective reactions were carried out in special plate reactors and compared with those of catalytic powders. The study shows that the coating of a metallic substrate by a catalyst is not straightforward and requires specific studies dealing with both chemistry (chemical affinity between substrate and catalytic layers) and catalytic engineering (catalytic performance in taylor-made reactors)

Preparation of NiNbO/AISI-430 ferritic stainless steel monoliths for catalytic applications

AISI 430 ferritic stainless steel was used as a substrate to make catalytic monolithic structures. To increase the surface roughness of the substrate, the steel was oxidized at temperatures in the range of 900–940 °C and times in the range of 30–120 min. The oxide layer formed was characterized. Treatment at 940 °C for 60 min was found to be optimal for obtaining a Cr-rich rough oxide layer, with good adherence and homogeneity. Catalytic monoliths were prepared by dip-coating into four different slurries containing the Ni–Nb mixed oxide catalyst. The samples were characterized and tested in the oxidative dehydrogenation (ODH) of ethane to ethylene. The structured catalysts were active for the ODH of ethane, with very good selectivity to ethylene. The catalytic performance was remarkably constant for 170 h on stream at 400 °C.Fil: Santander, José Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentina. Universidad Nacional del Sur; ArgentinaFil: Lopez, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentina. Universidad Nacional del Sur; ArgentinaFil: Tonetto, Gabriela Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentina. Universidad Nacional del Sur; ArgentinaFil: Pedernera, Marisa Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentina. Universidad Nacional del Sur; Argentin

Retrospective study 2005-2015 of all cases of fetal death occurred at 6523 gestational weeks, in Friusli Venezia Giulia, Italy

Background: Intrauterine fetal death (IUFD) is a tragic event and, despite efforts to reduce rates, its incidence remains difficult to reduce. The objective of the present study was to examine the etiological factors that contribute to the main causes and conditions associated with IUFD, over an 11-year period in a region of North-East Italy (Friuli Venezia Giulia) for which reliable data in available. Methods: Retrospective analysis of all 278 IUFD cases occurred between 2005 and 2015 in pregnancies with gestational age 65 23 weeks. Results: The incidence of IUFD was 2.8\u2030 live births. Of these, 30% were small for gestational age (SGA), with immigrant women being significantly over-represented. The share of SGA reached 35% in cases in which a maternal of fetal pathological condition was present, and dropped to 28% in the absence of associated pathology. In 78 pregnancies (28%) no pathology was recorded that could justify IUFD. Of all IUFDs, 11% occurred during labor, and 72% occurred at a gestational age above 30 weeks. Conclusion: The percentage of IUFD cases for which no possible cause can be identified is quite high. Only the adoption of evidence-based diagnostic protocols, with integrated immunologic, genetic and pathologic examinations, can help reduce this diagnostic gap, contributing to the prevention of future IUFDs